在其他函数中使用malloc更改字符串 [英] Change string with malloc in other function

问题描述

使用malloc时如何更改其他函数中的字符串?

how can I change string in other function when I am using malloc?

in main: 

char *myString;
changeString(myString);


changeString(char *myString){

    myString = malloc((size) * sizeof(char));
    myString[1] = 'a';

}

谢谢

推荐答案

C中的参数按值传递.因此，要在函数中修改变量，您必须将指针传递给它.例如，int *到int，char **到char *.

Parameters in C are passed by value. So to modify a variable within a function, you'll have to pass the pointer to it. For example, int * to int, and char ** to char *.

void changeString(char **myString){
    // free(*myString); // add when myString is allocated using malloc()
    *myString = malloc(2);
    (*myString)[0] = 'a';
    (*myString)[1] = '\0';
}

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